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I don't know if I'd care to purchase it later or go through the trouble of purchasing to resell it. I'd rather just get a better monthly lease payment. I'm working on a deal for a new 2013 that was manufactured in Aug 2012 so I'm hoping to leverage the fact it's been on the lot that long into a great cap cost basis.

As it's been said, the residuals are set by the bank and are non-negotiable.
Your numbers to negotiate are the purchase price of the vehicle and the money factor.
Since you can learn the "buy"rate of the money factor for the F07 here on Bimmerfest, you should use that to your advantage and try to get the best rate.
Simultaneously, you negotiate your purchase price (since you know the MSRP) up from the invoice price.
Lastly, check to see what incentives the dealer is getting for moving the vehicle. If there's trunk money or other incentives, use that to lower the purchase price.
It's probably worth trying to negotiate variables like doc fees, refusing to pay MACO, and seeing if you can reduce the lease acquisition fee (there's typically $200 markup).
If you already finance through BMWFS, they should wave security deposits.
Some people like using multiple security deposits (MSD's) to get a better money factor, but be warned that your money is then tied up for the length of the lease (for instance, if someone assumes your lease, the MSD's go with the vehicle until the lease concludes).